Then you are simply not very well informed. Problems with BTC transactions have happened repeatedly. Here is a great example of a successful 10k double spend during a chain fork: https://news.ycombinator.com/item?id=5372956 It was was made possible buy slightly different behaviours in the different client versions. The core developers had to get on IRC with the miner using the 0.8 version and talk them into giving up their (correct) chain to resolve this problem. Currency of the future!
This whole thing was possible because of an accidental fork of the chain which lasted a few hours. This is the only accidental fork that occurred in the last 3 years.
Details: https://github.com/bitcoin/bips/blob/master/bip-0050.mediawi...
It seems to me that this is the wrong question to ask. What you should be saying is "Thank you so very much for bringing us your prospective. How can we go about better informing people like you in the payments industry?"
What litaph91 described is a very real fear. Sure, all of us on Hacker News know that the fear is unfounded, but the general public doesn't know or understand everything that we do. Instead of arguing with one person, let's try to solve the wider problem, shall we?
A guarantee isn't what you want. Cash and card isn't guaranteed either — the cash might be counterfeit; the credit card might be stolen.
What you want is to reduce the rate of fraud. So let's compare the rates of fraud between bitcoin and cash/card. Credit card transactions are fraudulent around .1% of the time. [1] But I've never even heard of retail bitcoin fraud with zero-confirmation transactions. Have you?
You seem to be afraid of the wrong thing, and you don't seem to be basing your opinion any facts or statistics. It sounds like you're just untrusting of new technology. Yet you're on hacker news? This confuses me. How did you get here?
Similarly, your fear of replace-by-fee is very strange — that proposal is never going to happen. You don't have any faith in the bitcoin community, but you have faith in credit card companies not to raise fees or block your business? Why is that? Do you only trust old boys' clubs? Are you from the east coast? Are you a luddite?
[1] http://en.wikipedia.org/wiki/Credit_card_fraud